Highly magnetized neutron stars are a source of extreme transients observed in different bands, like the fast radio burst (FRB) and associated hard X-ray burst from the Galactic magnetar SGR 1935+2154. The origin of such outbursts, hard X-rays on the one hand and millisecond duration FRBs on the other hand, is still unknown. We present a global model for various kinds of such magnetar outbursting activities. Crustal surface motions can twist the inner magnetar magnetosphere by shifting the frozen-in footpoints of magnetic field lines. We discuss criteria for instabilities of 3D twisted flux bundles in the force-free dipolar magnetospheres and compare their energetic properties to observations of magnetar X-ray flares. We then connect such activities to recently developed FRB generation mechanisms in the outer magnetosphere of a magnetar. In a reconnection-mediated model, a magnetic pulse induced by a magnetar flare collides with the current sheet of the magnetar wind, compresses, and fragments it into a self-similar chain of magnetic islands. Time-dependent plasma currents created during their collisions produce relatively narrow-band GHz emission with luminosities sufficient to explain bright extragalactic FRBs. Alternatively, a so far unexplored shock-mediated FRB mechanism can convert magnetic perturbations of the magnetar wind to radio waves.
BIO
In my undergraduate studies at the Leibniz University of Hannover (Germany), I learned about the theory of General Relativity. In an exchange semester at Purdue University (USA), I had my first astrophysics lecture. With my master’s thesis at the University of Valencia (Spain), I started the exploration of magnetospheres of compact objects, at the time with a review of the Blandford/Znajek process. The following years of my Ph.D. with Prof. M. A. Aloy shaped a deep appreciation for the elegance of numerical techniques to answer exciting questions in astrophysics. Always determined to understand all their subtleties to the deepest level. After my first postdoc at Princeton University (USA), I am now applying this experience at Columbia University (USA) to advance our understanding of bursts and flares around magnetars by force-free and particle-in-cell simulations. I am excited to answer questions about dissipation in magnetospheres of compact objects with collaborators around the world.
Host: Xinyu Li
